以下，針對實施形態，參照附圖來作說明。
(第1實施形態)
第1圖，係對於第1實施形態之電池診斷系統1作展示。如第1圖所展示般地，電池診斷系統1，係具備：身為機器的車輛2、和充電裝置3及診斷伺服器5。於車輛2中，係搭載有電池組6。藉由從充電裝置3對電池組6供給電力，而使電池組6被充電。又，充電裝置3及診斷伺服器5，係能夠以有線或者是無線來相互交換資訊。
第2圖，係對於電池診斷系統1的控制系及通訊系作展示。如第2圖所展示般地，被搭載於車輛2的電池組6，係具備1個以上的電池7。於第2圖之一例中，於電池組6中，係電性地串聯連接有複數個電池7。1個以上之電池7的各者，係為例如鋰離子電池等之二次電池。另外，在某一例中，係亦可於電池組6中，僅設置有1個電池7。又，在另外的某一例中，於電池組6中，係電性地並聯連接有複數個電池7。另外，在另外的某一例中，於電池組6中，係形成有電性地串聯連接有複數個電池7的串聯連接構造以及電性地連接有複數個電池7的並聯連接構造之雙方。
又，在車輛2中，係形成有電性接點A1，在充電裝置3中，係形成有電性接點A2。在某一例中，係藉由將充電裝置3的供電插塞(未圖示)連接至車輛2的供電口(未圖示)，而使電性接點A1、A2對於彼此來電性地連接。藉由此，成為能夠從充電裝置3對於車輛2的電池組6(1個以上的電池7)供給電力，而成為能夠將電池組6充電。
充電裝置3，係具備電源電路11、驅動電路12、電流檢測電路13、電壓檢測電路15、控制器20及通訊電路30。驅動電路12，係具備電流產生電路17及輸出電路18。電流產生電路17，係具備轉換電路，轉換電路，係在電池組6之充電時，將從電源電路11所供給的電力轉換成輸出至電池組6的電力。電流產生電路17，係藉由對於輸出至電池組6的電力之電力轉換，而產生對於電池組6之輸出電流，亦即是產生電池組6之充電電流。
輸出電路18，係在電池組6之充電時，將以電流產生電路17之轉換電路所作了轉換的電力，輸出至電池組6。藉由此，在電流產生電路17所產生的輸出電流(充電電流)，係被供給至電池組6。又，對於電池組6，係與被供給來自輸出電路18之輸出電流一事相互同步地而被施加有來自輸出電路18之輸出電壓，亦即是電池組6之充電電壓。電流檢測電路13，係檢測出來自輸出電路18之輸出電流(電池組6之充電電流)。又，電壓檢測電路15，係檢測出來自輸出電路18之輸出電壓(電池組6之充電電壓)。
控制器20，例如係構成電腦。控制器20，係具備：包含CPU(Central Processing Unit)、ASIC(Application Specific Integrated Circuit)或者是FPGA(Field Programmable Gate Array)等之處理器或者是積體電路(控制電路)、以及記憶體等之記憶媒體。被設置在控制器20的處理器或者是積體電路，係可為1個，亦可為複數個。控制器20，係藉由執行被記憶在記憶媒體等之程式等，而進行處理。
控制器20，係具備基準電流設定部21、電流波形設定部22、電流波形重疊部23、輸出電流設定部25、電流監視部27及電壓監視部28。基準電流設定部21、電流波形設定部22、電流波形重疊部23、輸出電流設定部25、電流監視部27及電壓監視部28之各者，係執行藉由控制器20之處理器等所進行的處理之一部分。
基準電流設定部21，係設定關聯於來自輸出電路18之輸出電流而成為基準的基準電流。基準電流設定部21，係藉由基準電流設定部21所設定的基準電流為直流。基準電流所流動的方向，係與在電池組6之充電中電流所流動的方向為相同，並與在來自電池組6之放電中電流所流動的方向為相反方向。基準電流設定部21，係取得指令電流值，並在使基準電流之電流值與指令電流值一致的狀態下，設定基準電流(基準電流軌跡)。
在此，於某一例中，係在車輛2或者是充電裝置3之使用者介面(未圖示)中，由作業者等來輸入關聯於充電的操作指令。接著，基準電流設定部21，係根據關聯於充電的操作指令，來取得指令電流值。於另外之某一例中，控制器20，係取得搭載有被作充電的電池組6之車輛2的種類。接著，控制器20，係根據被記憶在記憶媒體等的資料，針對從充電開始起而相對於經過時間之輸出電流(充電電流)的關係，來選擇與車輛的種類相對應的模型。接著，控制器20，係根據所選擇的模型來設定指令電流值，基準電流設定部21，係取得所設定的指令電流值。
電流波形設定部22，係能夠取得波形設定指令。電流波形設定部22，係根據取得了波形設定指令一事，來設定頻率(特定之頻率)fa的電流波形。電流波形，係為於每隔半週期(1/2fa)使電流所流動的方向作變化的交流。於某一例中，頻率fa之矩形波電流，係作為電流波形而被設定。電流波形重疊部23，係根據電流波形被作了設定一事，來使電流波形設定部22所設定的電流波形與基準電流設定部21所設定的基準電流重疊。藉由此，而設定使頻率fa的電流波形與基準電流重疊的重疊電流。接著，電流波形重疊部23，係將所設定的重疊電流(重疊電流軌跡)傳達至輸出電流設定部25。
在此，於某一例中，控制器20，係根據關聯於前述之以使用者介面所輸入的充電之操作指令，來取得使電流波形與基準電流重疊的時機。接著，控制器20，係在使電流波形重疊的時機產生波形設定指令，電流波形設定部22，係取得所產生的波形設定指令。於另外的某一例中，控制器20，係根據被記憶在記憶媒體等的資料，針對使電流波形與基準電流重疊的時機，來選擇與車輛的種類相對應的模型。接著，控制器20，係根據所選擇的模型，在使電流波形重疊的時機產生波形設定指令，電流波形設定部22，係取得所產生的波形設定指令。又，在並未藉由電流波形設定部22而取得波形設定指令的情況，亦即是並非為使電流波形與基準電流重疊的時機的情況時，電流波形設定部22，係並不設定電流波形，電流波形重疊部23，係並不使電流波形與基準電流重疊。因此，藉由基準電流設定部21所設定的基準電流，會被傳達至輸出電流設定部25。
第3圖，係對於藉由基準電流設定部21所設定的基準電流(基準電流軌跡)之其中一例作展示，第4圖，係對於藉由電流波形設定部22所設定的電流波形之其中一例作展示。第5A圖，係對於使第4圖之電流波形與第3圖之基準電流重疊的重疊電流(重疊電流軌跡)作展示，第5B圖，係將第5A圖之區域B1放大來作展示。於第3圖至第5B圖中，橫軸代表以充電開始時作為基準之時間t，縱軸代表電流I。於第3圖至第5B圖中，將基準電流所流動的方向作為正方向來展示。於第3圖之一例中，基準電流設定部21，係於在時間ta與時間tb之間使電流值(指令電流值)成為值Ia且經時性地成為一致的狀態下設定基準電流。又，於第4圖之一例中，電流波形設定部22，係在時間ta與時間tb之間將頻率fa的矩形波電流作為電流波形來設定。
在此，所設定的電流波形之振幅Ib，相較於在時間ta與時間tb之間的基準電流之電流值(Ia)，係較小。於某一例中，電流波形設定部22，係將電流波形(矩形波電流)之振幅Ib，設定成基準電流之電流值Ia的5%以下。亦即是，電流波形之波峰-峰值(2Ib)，係被設定為基準電流之電流值Ia的10%以下。在波形設定指令中，係包含關聯於電流波形之振幅的資訊。電流波形設定部22，係根據關聯於所取得之電流波形的振幅之資訊，來設定電流波形的振幅。
由於是如前述般地設定電流波形，因此如第5A圖及第5B圖所展示般地，重疊電流，係設定成使重疊電流所流動的方向經時性地持續與基準電流所流動的方向一致之狀態。亦即是，在將朝向基準電流所流動的方向之電流的電流值設為正，且將朝向與基準電流所流動的方向為相反方向之電流的電流值設為負的情況，重疊電流的電流值，係經時性地持續被維持在大於零(正的值)。因此，在第5A圖及第5B圖之一例中，在時間ta與時間tb之間的任何時間點，重疊電流所流動的方向都會與基準電流所流動的方向一致。另外，在第5A圖及第5B圖之重疊電流中，係被設定有「在時間ta與時間tb之間，以值Ia作為中心，亦即是在上限值(Ia+Ib)與下限值(Ia-Ib)之間作週期性地變化的電流波形(矩形波電流)」。並且，所設定的電流波形，係以1/fa為一週期，作週期性地變化。
另外，在第3圖至第5B圖之一例中，係於基準電流中在電流值經時性地成為一定的區域處使電流波形重疊，但是，並不限定於此。在某一例中，係於基準電流中在電流值經時性地減少的區域處使電流波形重疊。即使是在此情況中，亦同樣的，重疊電流，係被設定成使重疊電流所流動的方向經時性地持續與基準電流所流動的方向一致之狀態。並且，電流波形(矩形波電流)之振幅，係被設定成基準電流之電流值的5%以下。
輸出電流設定部25，係設定從輸出電路18對於電池組6之輸出電流的目標電流值(目標軌跡)。並且，輸出電流設定部25，係在以作了設定的目標電流值而使輸出電流被作輸出的狀態下，控制電流產生電路17之驅動，並控制對於電池組6之輸出。在此，在藉由波形設定指令來使電流波形設定部22設定電流波形的情況時，輸出電流設定部25，係在藉由電流波形重疊部23而被作了設定的重疊電流從輸出電路18而被輸出的狀態下，控制對於電池組6之輸出電流。在此情況，重疊電流之經時性的變化之軌跡，係成為輸出電流之經時性的變化之目標軌跡。另一方面，在並未藉由電流波形設定部22來設定電流波形的情況時，輸出電流設定部25，係在藉由基準電流設定部21而被作了設定的基準電流從輸出電路18而被輸出的狀態下，控制對於電池組6之輸出電流。在此情況，基準電流之經時性的變化之軌跡，係成為輸出電流之經時性的變化之目標軌跡。
電流監視部27，係針對來自輸出電路18之輸出電流(電池組6之充電電流)，來取得電流檢測電路13之檢測結果。亦即是，電流監視部27，係取得輸出電流之檢測電流值。電壓監視部28，係針對與來自輸出電路18之輸出電流(電池組6之充電電流)相互同步的輸出電壓(充電電壓)，來取得電壓檢測電路15之檢測結果。亦即是，電壓監視部28，係取得輸出電壓之檢測電壓值。
又，輸出電流設定部25，係從電流監視部27取得輸出電流之檢測電流值。並且，輸出電流設定部25，係針對輸出電流，來將所設定的目標電流值與檢測電流值作比較，而取得目標電流值與檢測電流值之偏差。接著，輸出電流設定部25，係在偏差接近零的狀態下，控制電流產生電路17之驅動，並控制來自輸出電路18之輸出電流。亦即是，輸出電流設定部25，係關聯於輸出電流(充電電流)之輸出，而進行反饋控制。例如，在第5A圖及第5B圖等之重疊電流被作了設定的情況時，輸出電流設定部25，係在輸出電流接近所設定了的重疊電流之狀態下，進行輸出電流之反饋控制。又，在被設定有相對於基準電流之電流值而使電流波形之振幅成為5%以下的重疊電流的情況時，輸出電流設定部25，係在輸出電流之電流值與基準電流之電流值(指令電流值)之間的差落在5%以下的狀態下進行反饋控制。
電流監視部27，係根據所取得的輸出電流之檢測電流值，來檢測輸出電流之經時性的變化。藉由此，而可取得並計測輸出電流之經時性的變化。在此，即使是在作了設定的重疊電流被作輸出的狀態下進行輸出電流的控制，實際上在被作輸出的輸出電流中，除了與基準電流重疊的頻率fa之電流波形的成分以外，進而也可能包含有電流波形之高諧波的成分及雜訊等。因此，輸出電流之經時性的變化，與被作了設定的重疊電流之經時性的變化，係可能相異。在某情況中，即便是被設定有使頻率fa之矩形波與基準電流重疊的重疊電流，也可能會作為輸出電流之經時性的變化，而取得使接近三角波或者是鋸齒波的電流波形與基準電流重疊的計測資料。在此，於電流波形之高諧波的成分中，係可列舉頻率fa之奇數倍的頻率(3fa、5fa等)之成分等。
第6A圖，係對於使第5A圖及第5B圖之重疊電流作為輸出電流而被作了輸出的情況時之輸出電壓之經時性的變化之理論模型作展示，第6B圖，係將第6A圖的區域B2放大來作展示。於第6A圖及第6B圖中，橫軸代表以充電開始時作為基準之時間t，縱軸代表電壓V。在第6A圖及第6B圖的輸出電壓之理論模型中，在時間ta與時間tb之間，係出現與電流波形(矩形波電流)相對應之頻率fa的成分。在此，在將並不使電流波形重疊之第3圖的基準電流作為輸出電流而輸出的情況時之理論模型中，輸出電壓，在時間ta與時間tb之間，係如同函數Va(t)般地作經時性地變化。在第6A圖及第6B圖的輸出電壓之理論模型中，由於係出現有頻率fa的成分，因此在時間ta與時間tb之間，係形成有以函數Va(t)為中心來作週期性地變化之電壓波形。並且，時間ta與時間tb之間的電壓波形，係以1/fa為一週期，作週期性地變化。
電壓監視部28，係根據所取得的輸出電壓之檢測電壓值，來檢測與輸出電流同步的輸出電壓之經時性的變化。藉由此，而可取得及計測輸出電壓之經時性的變化。在此，即使是在使所設定的重疊電流被作輸出的狀態下進行輸出電流的控制，實際上在所計測的輸出電壓中，亦係與輸出電流同樣地，除了與電流波形相對應的頻率fa的成分以外，進而也可能包含有頻率fa的成分之高諧波的成分及雜訊等。因此，輸出電壓之經時性的變化，與對應於被作了設定的重疊電流之理論模型中之經時性的變化，係可能相異。在某狀況中，即使是在第5A圖及第5B圖之重疊電流被作輸出的狀態下進行控制，也可能會作為輸出電壓之經時性的變化而取得與第6A圖及第6B圖之理論模型相異的計測資料。在此，於頻率fa之高諧波之成分中，係可列舉頻率fa之奇數倍的頻率(3fa、5fa等)之成分等。
電流監視部27，係將關聯於所取得的輸出電流之經時性的變化之計測資料等的輸出電流之經時性的變化之資訊，經由通訊電路30，來輸出至充電裝置3的外部。又，電壓監視部28，係將關聯於所取得的輸出電壓之經時性的變化之計測資料等的輸出電壓之經時性的變化之資訊，經由通訊電路30，來輸出至充電裝置3的外部。藉由此，關聯於輸出電流及輸出電壓之各自的經時性的變化之資訊等，係被送訊至充電裝置3之外部的電腦等。
又，控制器20，係亦可將關聯於輸出電流及輸出電壓之各自的經時性的變化之資訊，取代輸出至充電裝置3的外部一事，而記憶於記憶媒體等，或者是除了輸出至充電裝置3的外部以外亦更進而記憶於記憶媒體等。此時，前述之資訊，係亦可暫時性地被記憶在記憶媒體等。
第7圖，係對於藉由控制器20而進行之關聯於電池組6的充電之處理作展示。在第7圖所示之處理中，控制器20，係對於電池組6之充電指令是否被產生，亦即是充電指令是否為ON一事作判斷(S101)。於某一例中，係根據前述之以使用者介面所輸入的操作指令，來產生充電指令。在另外之某一例中，係根據供電插塞被連接至車輛2的供電口(未圖示)而使電性接點A1、A2相互被作電性連接一事，來產生充電指令。
在產生有充電指令的情況(S101-Yes)，基準電流設定部21，係關聯於對於電池組6之輸出電流(充電電流)，來取得指令電流值(S102)。接著，基準電流設定部21，係將所取得的指令電流值作為基準電流之電流值來作設定，而設定基準電流(S103)。接著，電流波形設定部22，係對於波形設定指令是否被產生，亦即是波形設定指令是否為ON一事作判斷(S104)。波形設定指令，係與前述之例中的任一例同樣地被產生。
在產生有波形設定指令的情況(S104-Yes)，電流波形設定部22，係取得波形設定指令，並根據波形設定指令，來設定頻率(特定的頻率)fa之電流波形(S105)。電流波形之振幅等，係與前述之例中的任一例同樣地被設定。接著，電流波形重疊部23，係將在S105所設定的電流波形與在S103所設定的基準電流重疊(S106)。藉由此，而設定使頻率fa的電流波形與基準電流重疊的重疊電流。重疊電流，係被設定成使重疊電流所流動的方向經時性地持續與基準電流所流動的方向一致之狀態。接著，輸出電流設定部25，係在使作了設定的重疊電流被作輸出的狀態下，控制電流產生電路17之驅動，並控制從輸出電路18對於電池組6之輸出(S107)。亦即是，在作了設定的重疊電流被作輸出的狀態下控制輸出電流。
另一方面，在未產生波形設定指令的情況(S104-No)，輸出電流設定部25，係於在S103所設定的基準電流被輸出的狀態下，控制電流產生電路17之驅動，並控制從輸出電路18對於電池組6之輸出(S108)。亦即是，在作了設定的基準電流被作輸出的狀態下控制輸出電流。
接著，在進行著S107或者是S108之輸出控制的狀態下，電流監視部27，係取得輸出電流之檢測電流值，電壓監視部28，係取得輸出電壓之檢測電壓值(S109)。接著，處理係前進至S101。接著，在產生有充電指令的情況時(S101-Yes)，係再度進行S102以後的處理。接著，在進行S107或者是S108之輸出控制的狀態下，係進行根據目標電流值與檢測電流值之間之偏差等所致之前述之反饋控制。此時，輸出電流設定部25，係亦可在使輸出電流之電流值(檢測電流值)與基準電流之電流值(指令電流值)之間的差落在5%以下的狀態下進行反饋控制。
當於S101中並未產生充電指令的情況(S101-No)，控制器20(輸出電流設定部25)，係使從輸出電路18所對於電池組6之輸出停止(S110)。藉由此，而使電池組6之充電停止。
如第2圖所展示般地，診斷伺服器5，係具備傅立葉轉換器31及演算器32。傅立葉轉換器31及演算器32之各者，係具備「包含CPU、ASIC或者是FPGA等之處理器或者是積體電路(演算電路)」及「記憶體等之記憶媒體」，並進行後述之演算處理。傅立葉轉換器31及演算器32之各者，係實施藉由診斷伺服器5來進行的處理，亦即是關聯於電池組6(1個以上的電池7)之狀態(劣化狀態)的診斷之處理的一部分。
第8圖，係對於傅立葉轉換器31及演算器32之各者所進行的處理作展示。如第8圖所展示般地，診斷伺服器5的傅立葉轉換器31，係從充電裝置3之通訊電路30，取得關聯於輸出電流之經時性的變化之資訊Iα(t)。於某一例中，資訊Iα(t)，係為藉由電流監視部27所計測的輸出電流之經時性的變化之計測資料。在此，在輸出電流之經時性的變化之計測資料中，頻率fa之電流波形的部分等，係相對於以零為中心的電流波形，而作與基準電流之電流值相同或者是略相同的大小之量之偏離。因此，於另外之某一例中，係與頻率fa之電流波形的部分等之前述的偏離相對應地，來修正前述之計測資料。接著，從計測資料而進行了前述之修正的資料，係於傅立葉轉換器31中，作為資訊Iα(t)而被取得。
接著，傅立葉轉換器31，係將資訊Iα(t)作傅立葉轉換(S121)。藉由此，而產生關於輸出電流之頻譜Iβ(f)，而算出輸出電流之頻率特性。在此，f，係為表示頻率的變數。頻譜Iβ(f)，係包含頻率(特定之頻率)fa的成分，及頻率fa之整數倍的1個以上之頻率的成分。於某一例中，輸出電流之頻譜Iβ(f)，係包含頻率fa的成分，及頻率fa的奇數倍之頻率(3fa、5fa等)的成分。
又，傅立葉轉換器31，係從充電裝置3之通訊電路30，取得關聯於輸出電壓之經時性的變化之資訊Vα(t)。於某一例中，資訊Vα(t)，係為藉由電壓監視部28所計測的輸出電壓之經時性的變化之計測資料。又，於另外之某一例中，輸出電流之計測資料係如前述般地被修正成資訊Iα(t)，並與資訊Iα(t)之修正相對應地，來修正前述之輸出電壓的計測資料。接著，從計測資料而進行了前述之修正的資料，係於傅立葉轉換器31中，作為資訊Vα(t)而被取得。
接著，傅立葉轉換器31，係將資訊Vα(t)作傅立葉轉換(S122)。藉由此，而產生針對輸出電壓之頻譜Vβ(f)，而算出輸出電壓之頻率特性。頻譜Vβ(f)，係包含頻率(特定之頻率)fa的成分，及頻率fa之整數倍的1個以上之頻率的成分。於某一例中，輸出電壓之頻譜Vβ(f)，係包含頻率fa的成分，及頻率fa的奇數倍之頻率(3fa、5fa等)的成分。
接著，演算器32，係取得輸出電流之頻譜Iβ(f)及輸出電壓之頻譜Vβ(f)，並使用頻譜Iβ(f)、Vβ(f)來進行演算(S123)。於在S123之演算中，係從頻譜Iβ(f)，算出關聯於輸出電流之經時性的變化之資訊Iα(t)的自相關函數Corr(I, I)。接著，從頻譜Iβ(f)、Vβ(f)，算出關聯於輸出電流之經時性的變化之資訊Iα(t)與關聯於輸出電壓之經時性的變化之資訊Vα(t)之間之互相關函數Corr(I, V)。
接著，演算器32，係使用所算出的自相關函數Corr(I, I)及互相關函數Corr(I, V)來進行演算(S124)。藉由S124的演算，而算出電池組6(1個以上的電池7)之阻抗特性。於某一例中，係藉由將互相關函數Corr(I, V)除以自相關函數Corr(I, I)，來針對在頻譜Iβ(f)、Vβ(f)中包含有成分(頻譜成分)的頻率之各者而算出阻抗。診斷伺服器5，係根據所算出的阻抗特性，來對電池組6的狀態(劣化狀態)作診斷。
另外，在將輸出電流之計測資料作為資訊Iα(t)來使用的情況時，頻率fa之電流波形的部分等相對於以零為中心之電流波形而作了偏離的資訊Iα(t)，係被作傅立葉轉換。在此情況中，係將藉由傅立葉轉換所取得的頻譜Iβ(f)之資料，與頻率fa之電流波形的部分等之前述之偏離相對應地來作修正。接著，使用從頻譜Iβ(f)之資料而進行了前述之修正的資料，來算出阻抗特性。又，在將輸出電壓之計測資料作為資訊Vα(t)來使用，並藉由傅立葉轉換來取得頻譜Vβ(f)的情況時，亦係與將輸出電流之計測資料作為資訊Iα(t)來使用的情況同樣地，對頻譜Vβ(f)之資料作適當修正。接著，使用從頻譜Vβ(f)之資料而進行了前述之修正的資料，來算出阻抗特性。
如前述般地，於本實施形態中，係與所謂的矩形波阻抗法同樣地，根據資訊Iα(t)、Vα(t)來算出電池組6之阻抗特性。在此，關於根據矩形波阻抗法及阻抗特性所致的電池(電池組)之狀態的診斷，係被揭示於參考文獻1(日本特開2014-126532號公報)及參考文獻2(Electrochimica Acta vol.246 (2017) p.800‐p.811)中。於本實施形態中，係控制對於電池組6之輸出電流。因此，在阻抗特性之算出中，係使用有關聯於輸出電流之經時性的變化之資訊Iα(t)的自相關函數Corr(I, I)。
如前述般地，於本實施形態中，使頻率fa的電流波形(矩形波電流)與身為直流之基準電流作了重疊的重疊電流，係藉由電流波形重疊部23而被設定。接著，輸出電流設定部25，係在所設定的重疊電流被作輸出的狀態下，控制對於電池組6之輸出電流，並藉由輸出電流來將電池組6充電。藉由如前述一般地來控制輸出電流，而成為能夠將輸出電流之經時性的變化之計測資料及與輸出電流同步的輸出電壓之經時性的變化之計測資料，使用於電池組6之阻抗特性的算出等之電池組6的狀態之診斷中。因此，係使被使用於電池組6之狀態的診斷之資訊成為在電池組6之充電時能夠容易地取得。
又，於本實施形態中，電流波形重疊部23，係在使重疊電流所流動的方向經時性地持續與基準電流所流動的方向一致之狀態下，設定重疊電流。因此，即便是在重疊電流被作輸出的狀態下控制輸出電流，也能對電池組6經時性地持續供給輸出電流，而使電池組6經時性地持續被充電。藉由此，而使電池組6被適當地充電。
又，於本實施形態中，電流波形設定部22，係將電流波形之振幅，設定成相對於基準電流之電流值而為5%以下。因此，藉由在使重疊電流被作輸出的狀態下控制輸出電流，而使輸出電流之電流值與基準電流之電流值(於充電中之指令電流值)之間的偏差變小。因而，使電池組6被更適當地充電。
又，於本實施形態中，輸出電流設定部25，係在目標電流值與檢測電流值之間的偏差接近零的狀態下，針對輸出電流進行反饋控制。例如，在設定有相對於基準電流之電流值而電流波形之振幅成為5%以下的重疊電流的情況，輸出電流設定部25，係在使輸出電流之電流值(檢測電流值)與基準電流之電流值(於充電中之指令電流值)之間的差落在5%以下的狀態下，進行反饋控制。藉由此，而使輸出電流之電流值與基準電流之電流值(於充電中之指令電流值)之間的偏差更進一步變小，使電池組6被更適當地充電。
又，於本實施形態中，在未產生波形設定指令的情況等，係不設定電流波形，輸出電流設定部25，係在作了設定的基準電流被作輸出的狀態下，控制對於電池組6之輸出電流。因此，能夠因應於是否有必要取得被使用於電池組6的診斷之資訊等的狀況，來選擇關聯於對於電池組6之輸出電流的控制模型。
又，於本實施形態中，診斷伺服器5，係根據輸出電流之經時性的變化之計測資料及輸出電壓之經時性的變化之計測資料，如前述般地算出電池組6之阻抗特性。因此，使用計測資料來適當地算出阻抗特性，並適當地診斷電池組6之狀態。
(變形例)
另外，在某變形例中，電流波形設定部22，係除了頻率(特定之頻率)fa的電流波形以外，進而設定頻率fa之整數倍之1個以上的頻率之電流波形。接著，電流波形重疊部23，係除了頻率fa的電流波形以外，進而使頻率fa之整數倍之1個以上的頻率之電流波形與基準電流重疊，而設定重疊電流。在本變形例中，亦同樣的，輸出電流設定部25，係在所設定的重疊電流被作輸出的狀態下，控制對於電池組6之輸出電流。
於本變形例中，係進行將除了頻率fa的電流波形以外更進而亦使頻率fa之整數倍之1個以上的頻率之電流波形作重疊的重疊電流輸出之控制。因此，藉由如前述之實施形態等般地算出輸出電流之頻譜Iβ(f)及輸出電壓之頻譜Vβ(f)，而成為能夠在頻譜Iβ(f)、Vβ(f)之各者中，以頻率fa之整數倍的頻率中之更多的頻率，來取得成分(頻譜成分)。藉由此，以頻率fa之整數倍的頻率中之更多的頻率來算出阻抗，而可更適當地診斷電池組6之狀態(劣化狀態)。
在某一例中，係設定有除了頻率(第1頻率)fa的電流波形以外更進而使頻率fa之整數倍之2個的頻率fb、fc(fc＞fb)之電流波形與基準電流作了重疊的重疊電流。接著，在作了設定的重疊電流被作輸出的狀態下，控制對於電池組6之輸出電流。於此情況中，頻率(第2頻率)fb，較理想為頻率fa的偶數倍，例如，係為頻率2fa。接著，頻率(第3頻率)fc，較理想為頻率fa的偶數倍，且為頻率fb的偶數倍，例如，係為頻率4fa(=2fb)。
藉由如前述般地設定頻率fa～fc，頻率fa之奇數倍的頻率之各者，係與頻率fb、頻率fb的奇數倍之頻率、頻率fc、頻率fc的奇數倍之頻率中的任一頻率皆相異。藉由此，而成為能夠於如前述之實施形態等般地所算出的頻譜Iβ(f)、Vβ(f)之各者中，以頻率fa的整數倍之頻率中之更多的頻率來取得成分。藉由此，以頻率fa之整數倍的頻率中之更多的頻率來算出阻抗，而可更適當地診斷電池組6之狀態(劣化狀態)。
又，在某變形例中，係亦可使傅立葉轉換器31及演算器32被搭載於充電裝置3。於本變形例中，係藉由充電裝置3，來算出輸出電流之頻率特性以及輸出電壓之頻率特性，並算出電池組6之阻抗特性。又，在另外的某變形例中，係亦可使傅立葉轉換器31及演算器32之其中一方被搭載於充電裝置3。
又，前述之對於充電組6之輸出電流(充電電流)的控制，係不僅適用於車輛2之電池組6的充電，也能夠適用於被搭載在車輛2以外的機器之電池組的充電。
若是依據該等之至少其中一個實施形態或者是實施例，則充電裝置及充電方法，係使特定之頻率的電流波形與身為直流的基準電流重疊，並使作了重疊的重疊電流，被設定成使重疊電流所流動的方向經時性地持續與基準電流所流動的方向一致之狀態。接著，在作了設定的重疊電流被作輸出的狀態下，控制對於電池組之輸出電流，藉由輸出電流來使電池組被充電。藉由此，而可提供一種使被使用於電池組之狀態的診斷之資訊成為在電池組之充電時能夠容易地取得的充電裝置及充電方法。
雖然是對於本發明之幾個實施形態作了說明，但是，該等實施形態，係作為例子而揭示者，並非意圖對發明之範圍作限定。該等新穎的實施形態，係能夠以其他之各種形態而被實施，且在不脫離發明之要旨的範圍內，可進行各種的省略、置換、變更。該等實施形態或是其之變形，係被包含在發明之範圍或是要旨中，並且也被包含在申請專利範圍所記載的發明與其之均等的範圍內。 Hereinafter, embodiments will be described with reference to the drawings. (First Embodiment) Fig. 1 shows a battery diagnosis system 1 according to a first embodiment. As shown in FIG. 1 , the battery diagnosis system 1 includes a vehicle 2 as a machine, a charging device 3 , and a diagnosis server 5 . A battery pack 6 is mounted on the vehicle 2 . The battery pack 6 is charged by supplying electric power from the charging device 3 to the battery pack 6 . In addition, the charging device 3 and the diagnostic server 5 can exchange information with each other through wired or wireless. FIG. 2 shows the control system and communication system of the battery diagnosis system 1 . As shown in FIG. 2 , the battery pack 6 mounted on the vehicle 2 includes one or more batteries 7 . In the example shown in FIG. 2, a plurality of batteries 7 are electrically connected in series to the battery pack 6. Each of the one or more batteries 7 is a secondary battery such as a lithium ion battery. In addition, in a certain example, only one battery 7 may be provided in the battery pack 6 . In another example, a plurality of batteries 7 are electrically connected in parallel to the battery pack 6 . In another example, the battery pack 6 has both a series connection structure in which the plurality of batteries 7 are electrically connected in series and a parallel connection structure in which the plurality of batteries 7 are electrically connected. Also, in the vehicle 2 , an electrical contact A1 is formed, and in the charging device 3 , an electrical contact A2 is formed. In one example, the electrical contacts A1 and A2 are electrically connected to each other by connecting a power supply plug (not shown) of the charging device 3 to a power supply port (not shown) of the vehicle 2 . As a result, electric power can be supplied from the charging device 3 to the battery pack 6 (one or more batteries 7 ) of the vehicle 2 , and the battery pack 6 can be charged. The charging device 3 includes a power supply circuit 11 , a drive circuit 12 , a current detection circuit 13 , a voltage detection circuit 15 , a controller 20 and a communication circuit 30 . The drive circuit 12 includes a current generating circuit 17 and an output circuit 18 . The current generation circuit 17 includes a conversion circuit that converts the power supplied from the power supply circuit 11 into power output to the battery pack 6 when the battery pack 6 is charged. The current generating circuit 17 generates an output current for the battery pack 6 by converting the power output to the battery pack 6 , that is, generates a charging current for the battery pack 6 . The output circuit 18 outputs the electric power converted by the conversion circuit of the current generating circuit 17 to the battery pack 6 when the battery pack 6 is charged. As a result, the output current (charging current) generated by the current generating circuit 17 is supplied to the battery pack 6 . Also, the battery pack 6 is supplied with the output voltage from the output circuit 18 , which is the charging voltage of the battery pack 6 , in synchronization with the supply of the output current from the output circuit 18 . The current detection circuit 13 detects the output current (charging current of the battery pack 6 ) from the output circuit 18 . Also, the voltage detection circuit 15 detects the output voltage from the output circuit 18 (the charging voltage of the battery pack 6). The controller 20 constitutes, for example, a computer. The controller 20 is equipped with: a processor including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or an integrated circuit (control circuit), and a memory, etc. memory media. The processor or integrated circuit provided in the controller 20 may be one or plural. The controller 20 performs processing by executing a program or the like stored in a storage medium or the like. The controller 20 includes a reference current setting unit 21 , a current waveform setting unit 22 , a current waveform superimposing unit 23 , an output current setting unit 25 , a current monitoring unit 27 and a voltage monitoring unit 28 . Each of the reference current setting unit 21, the current waveform setting unit 22, the current waveform superimposing unit 23, the output current setting unit 25, the current monitoring unit 27, and the voltage monitoring unit 28 is executed by the processor of the controller 20, etc. part of the processing. The reference current setting unit 21 sets a reference current that is a reference in relation to the output current from the output circuit 18 . The reference current setting part 21 is such that the reference current set by the reference current setting part 21 is a direct current. The direction in which the reference current flows is the same as the direction in which the current flows during charging of the battery pack 6 and the opposite direction to the direction in which the current flows during discharge from the battery pack 6 . The reference current setting unit 21 acquires a command current value, and sets a reference current (reference current locus) in a state where the current value of the reference current matches the command current value. Here, in a certain example, an operator or the like inputs an operation command related to charging on a user interface (not shown) of the vehicle 2 or the charging device 3 . Next, the reference current setting unit 21 obtains a command current value based on an operation command related to charging. In another example, the controller 20 acquires the type of the vehicle 2 on which the battery pack 6 to be charged is mounted. Next, the controller 20 selects a model corresponding to the type of vehicle with respect to the relationship of the output current (charging current) with respect to the elapsed time from the start of charging based on the data stored in the storage medium or the like. Next, the controller 20 sets the command current value based on the selected model, and the reference current setting unit 21 acquires the set command current value. The current waveform setting unit 22 is capable of acquiring a waveform setting command. The current waveform setting unit 22 sets the current waveform at the frequency (specific frequency) fa based on the acquisition of the waveform setting command. The current waveform is an alternating current that changes the direction of current flow every half cycle (1/2fa). In a certain example, a rectangular wave current of frequency fa is set as a current waveform. The current waveform superimposing unit 23 superimposes the current waveform set by the current waveform setting unit 22 and the reference current set by the reference current setting unit 21 based on the fact that the current waveform is set. Thereby, the superimposition current which superimposes the current waveform of frequency fa and a reference current is set. Next, the current waveform superimposing unit 23 transmits the set superimposed current (superimposed current trajectory) to the output current setting unit 25 . Here, in a certain example, the controller 20 obtains the timing for superimposing the current waveform and the reference current according to the operation command related to the charging input through the user interface mentioned above. Next, the controller 20 generates a waveform setting command when the current waveforms are superimposed, and the current waveform setting unit 22 acquires the generated waveform setting command. In another example, the controller 20 selects a model corresponding to the type of vehicle with respect to the timing at which the current waveform is superimposed on the reference current based on data stored in a storage medium or the like. Next, the controller 20 generates a waveform setting command at the timing of superimposing the current waveforms based on the selected model, and the current waveform setting unit 22 acquires the generated waveform setting command. Also, when the waveform setting instruction is not obtained by the current waveform setting section 22, that is, when it is not the timing to overlap the current waveform and the reference current, the current waveform setting section 22 does not set the current waveform. The current waveform superimposing unit 23 does not superimpose the current waveform on the reference current. Therefore, the reference current set by the reference current setting unit 21 is transmitted to the output current setting unit 25 . Fig. 3 shows an example of the reference current (reference current trajectory) set by the reference current setting part 21, and Fig. 4 shows an example of the current waveform set by the current waveform setting part 22 for display. Fig. 5A shows the superimposed current (overlapped current track) in which the current waveform in Fig. 4 overlaps the reference current in Fig. 3 , and Fig. 5B shows an enlarged region B1 in Fig. 5A. In FIGS. 3 to 5B, the horizontal axis represents the time t based on the start of charging, and the vertical axis represents the current I. In FIGS. 3 to 5B, the direction in which the reference current flows is shown as the positive direction. In the example shown in FIG. 3 , the reference current setting unit 21 sets the reference current so that the current value (command current value) becomes the value Ia between the time ta and the time tb and is consistent over time. In addition, in the example shown in FIG. 4, the current waveform setting unit 22 sets a rectangular wave current with a frequency fa as the current waveform between the time ta and the time tb. Here, the amplitude Ib of the set current waveform is smaller than the current value (Ia) of the reference current between time ta and time tb. In a certain example, the current waveform setting unit 22 sets the amplitude Ib of the current waveform (rectangular wave current) to 5% or less of the current value Ia of the reference current. That is, the peak-to-peak value (2Ib) of the current waveform is set to be 10% or less of the current value Ia of the reference current. In the waveform setting command, information related to the amplitude of the current waveform is included. The current waveform setting unit 22 sets the amplitude of the current waveform based on information related to the acquired amplitude of the current waveform. Since the current waveform is set as described above, as shown in FIG. 5A and FIG. 5B, the superimposed current is set so that the direction in which the superimposed current flows continues to coincide with the direction in which the reference current flows over time. state. That is, when the current value of the current flowing in the direction in which the reference current flows is positive, and the current value of the current flowing in the direction opposite to the direction in which the reference current flows is negative, the current of the superimposed current The value is maintained at a value greater than zero (positive value) over time. Therefore, in one example of FIG. 5A and FIG. 5B , at any time point between time ta and time tb, the direction in which the superimposed current flows is consistent with the direction in which the reference current flows. In addition, in the superimposed current in Fig. 5A and Fig. 5B, it is set that "between the time ta and the time tb, centering on the value Ia, that is, between the upper limit (Ia+Ib) and the lower limit A current waveform (rectangular wave current) that periodically changes between values (Ia-Ib)". Moreover, the set current waveform changes periodically with 1/fa as a cycle. In addition, in the example of FIG. 3 to FIG. 5B , the current waveforms are superimposed in the region where the current value becomes constant over time among the reference currents, but the present invention is not limited thereto. In a certain example, current waveforms are superimposed on a region where the current value decreases with time in the reference current. Even in this case, similarly, the superimposed current is set such that the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. In addition, the amplitude of the current waveform (rectangular wave current) is set to be 5% or less of the current value of the reference current. The output current setting unit 25 sets the target current value (target locus) of the output current from the output circuit 18 to the battery pack 6 . Furthermore, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output to the battery pack 6 in a state where the output current is output at the set target current value. Here, when the current waveform setting section 22 sets the current waveform by the waveform setting command, the output current setting section 25 outputs the superimposed current set by the current waveform superimposing section 23 from the output circuit 18 In the output state, the output current to the battery pack 6 is controlled. In this case, the track of the temporal change of the superimposed current becomes the target track of the temporal change of the output current. On the other hand, when the current waveform is not set by the current waveform setting unit 22 , the output current setting unit 25 receives the reference current set by the reference current setting unit 21 from the output circuit 18 In the output state, the output current to the battery pack 6 is controlled. In this case, the track of the temporal change of the reference current becomes the target track of the temporal change of the output current. The current monitoring unit 27 obtains the detection result of the current detection circuit 13 with respect to the output current from the output circuit 18 (the charging current of the battery pack 6 ). That is, the current monitoring unit 27 obtains the detected current value of the output current. The voltage monitoring unit 28 obtains the detection result of the voltage detection circuit 15 with respect to the output voltage (charging voltage) synchronized with the output current (charging current of the battery pack 6 ) from the output circuit 18 . That is, the voltage monitoring unit 28 obtains the detected voltage value of the output voltage. Furthermore, the output current setting unit 25 acquires the detected current value of the output current from the current monitoring unit 27 . Furthermore, the output current setting unit 25 compares the set target current value with the detected current value for the output current, and obtains the deviation between the target current value and the detected current value. Next, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output current from the output circuit 18 in a state where the deviation is close to zero. That is, the output current setting unit 25 performs feedback control in relation to the output of the output current (charging current). For example, when the superimposed current in FIG. 5A and FIG. 5B is set, the output current setting unit 25 performs feedback control of the output current in a state where the output current is close to the set superimposed current. Also, when an overlapping current is set such that the amplitude of the current waveform becomes 5% or less with respect to the current value of the reference current, the output current setting unit 25 sets the current value between the current value of the output current and the current value of the reference current ( Feedback control is performed when the difference between command current value) falls below 5%. The current monitoring unit 27 detects a temporal change in the output current based on the obtained detected current value of the output current. By doing so, it is possible to acquire and measure the temporal change of the output current. Here, even if the output current is controlled in a state where the set superimposed current is output, in the output current actually output, except for the component of the current waveform of the frequency fa superimposed on the reference current, Furthermore, it may also contain high harmonic components and noise of the current waveform. Therefore, the time-dependent change of the output current may be different from the time-dependent change of the set overlapping current. In some cases, even if the overlapping current is set so that the rectangular wave of frequency fa overlaps with the reference current, a current waveform close to a triangular wave or a sawtooth wave may be obtained as a change in the output current over time. Measurement data of reference current superimposition. Here, components of frequencies (3fa, 5fa, etc.) that are odd multiples of frequency fa are examples of the harmonic components of the current waveform. Fig. 6A shows a theoretical model of the time-dependent change of the output voltage when the overlapping current in Fig. 5A and Fig. 5B is output as the output current, and Fig. 6B shows the theoretical model of the change of the output voltage over time. Region B2 of Figure 6A is enlarged for illustration. In FIGS. 6A and 6B , the horizontal axis represents the time t based on the start of charging, and the vertical axis represents the voltage V. In the theoretical model of the output voltage in Fig. 6A and Fig. 6B, a component of frequency fa corresponding to the current waveform (rectangular wave current) appears between time ta and time tb. Here, in the theoretical model in which the reference current in Fig. 3 that does not overlap the current waveform is output as the output current, the output voltage is like a function Va(t) between time ta and time tb generally change over time. In the theoretical model of the output voltage in Figure 6A and Figure 6B, since the component of the existing frequency fa appears in the system, there is a periodicity centered on the function Va(t) between the time ta and the time tb. The voltage waveform of ground change. Moreover, the voltage waveform between time ta and time tb changes periodically with 1/fa as a period. The voltage monitoring unit 28 detects a temporal change in the output voltage in synchronization with the output current based on the obtained detected voltage value of the output voltage. Thereby, it is possible to acquire and measure the temporal change of the output voltage. Here, even if the output current is controlled in a state where the set superimposed current is output, in fact, the measured output voltage is the same as the output current, except for the frequency corresponding to the current waveform. In addition to the component of fa, there may be components of higher harmonics of the component of frequency fa, noise, and the like. Therefore, the time-dependent change of the output voltage may be different from the time-dependent change in the theoretical model corresponding to the set overlapping current. In a certain situation, even if the control is performed in the state where the overlapping current in Fig. 5A and Fig. 5B is output, the difference with Fig. 6A and Fig. 6B may be obtained as a change in the output voltage over time. Measurement data with different theoretical models. Here, among the high harmonic components of the frequency fa, components of frequencies (3fa, 5fa, etc.) that are odd multiples of the frequency fa are exemplified. The current monitoring unit 27 outputs the information on the temporal change of the output current, such as the acquired measurement data on the temporal change of the output current, to the outside of the charging device 3 via the communication circuit 30 . In addition, the voltage monitoring unit 28 outputs information on the temporal change in the output voltage, such as measurement data related to the obtained temporal change in the output voltage, to the charging device 3 via the communication circuit 30 . external. Thereby, the information etc. which relate to each temporal change of an output current and an output voltage are sent to the external computer etc. of the charging apparatus 3. As shown in FIG. In addition, the controller 20 may also store the information related to the temporal changes of the output current and the output voltage in a memory medium instead of outputting the information to the outside of the charging device 3, or in addition to outputting the information to the external charging device 3. In addition to the outside of the charging device 3, it is further stored in a storage medium or the like. At this time, the aforementioned information may also be temporarily memorized in a memory medium or the like. FIG. 7 shows the processing related to the charging of the battery pack 6 performed by the controller 20 . In the processing shown in FIG. 7, the controller 20 judges whether or not the charging command for the battery pack 6 is generated, that is, whether the charging command is ON (S101). In a certain example, the charging command is generated according to the aforementioned operation command input through the user interface. In another example, the charging command is generated based on the fact that the electrical contacts A1 and A2 are electrically connected to each other by connecting the power supply plug to the power supply port (not shown) of the vehicle 2 . When there is a charge command (S101-Yes), the reference current setting unit 21 acquires a command current value in relation to the output current (charging current) to the battery pack 6 (S102). Next, the reference current setting unit 21 sets the acquired command current value as the current value of the reference current to set the reference current ( S103 ). Next, the current waveform setting unit 22 judges whether the waveform setting command is generated, that is, whether the waveform setting command is ON (S104). The waveform setting command is generated in the same manner as any of the above-mentioned examples. When there is a waveform setting command (S104-Yes), the current waveform setting unit 22 acquires the waveform setting command, and sets the current waveform of frequency (specific frequency) fa according to the waveform setting command (S105). The amplitude and the like of the current waveform are set in the same manner as in any of the aforementioned examples. Next, the current waveform superimposing unit 23 superimposes the current waveform set in S105 and the reference current set in S103 (S106). Thereby, the superimposition current which superimposes the current waveform of frequency fa and a reference current is set. The superimposed current is set such that the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. Next, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output from the output circuit 18 to the battery pack 6 in a state where the set superimposed current is output (S107). That is, the output current is controlled in a state where the set superimposed current is output. On the other hand, when the waveform setting command is not generated (S104-No), the output current setting unit 25 controls the drive of the current generating circuit 17 under the condition that the reference current set in S103 is output, and controls the slave The output of the output circuit 18 to the battery pack 6 (S108). That is, the output current is controlled in a state where the set reference current is output. Next, in the state of performing the output control in S107 or S108, the current monitoring unit 27 obtains the detected current value of the output current, and the voltage monitoring unit 28 obtains the detected voltage value of the output voltage (S109). Next, the process proceeds to S101. Next, when there is a charging instruction (S101-Yes), the processing after S102 is performed again. Next, in the state where the output control in S107 or S108 is performed, the aforementioned feedback control based on the deviation between the target current value and the detected current value, etc. is performed. At this time, the output current setting unit 25 may perform feedback control in a state where the difference between the current value of the output current (detection current value) and the current value of the reference current (command current value) falls below 5%. . When the charging command is not generated in S101 (S101-No), the controller 20 (output current setting unit 25) stops the output from the output circuit 18 to the battery pack 6 (S110). As a result, charging of the battery pack 6 is stopped. As shown in FIG. 2 , the diagnosis server 5 includes a Fourier transformer 31 and a calculator 32 . Each of the Fourier converter 31 and the calculator 32 is equipped with "a processor including a CPU, ASIC, or FPGA, or an integrated circuit (calculation circuit)" and "a storage medium such as a memory", which will be described later. Calculus processing. Each of the Fourier converter 31 and the calculator 32 implements the processing performed by the diagnosis server 5, that is, the diagnosis related to the state (deterioration state) of the battery pack 6 (one or more batteries 7). part of the processing. FIG. 8 shows the processing performed by each of the Fourier transformer 31 and the arithmetic unit 32 . As shown in FIG. 8 , the Fourier converter 31 of the diagnostic server 5 obtains information Iα(t) related to the temporal change of the output current from the communication circuit 30 of the charging device 3 . In a certain example, the information Iα(t) is measurement data of a temporal change in the output current measured by the current monitoring unit 27 . Here, in the measurement data of the temporal change of the output current, the portion of the current waveform at the frequency fa, etc. is made to be the same or slightly the same as the current value of the reference current with respect to the current waveform centered on zero. The deviation of the size of the amount. Therefore, in another example, the above-mentioned measurement data is corrected in accordance with the above-mentioned deviation in the portion of the current waveform at the frequency fa. Next, data on which the above-mentioned correction has been performed from the measurement data is obtained as information Iα(t) in the Fourier transformer 31 . Next, the Fourier transformer 31 performs Fourier transformation on the information Iα(t) (S121). By doing this, a spectrum Iβ(f) of the output current is generated, and the frequency characteristic of the output current is calculated. Here, f is a variable indicating frequency. Spectrum Iβ(f) includes components of frequency (specific frequency) fa and components of one or more frequencies that are integer multiples of frequency fa. In a certain example, the frequency spectrum Iβ(f) of the output current includes components of the frequency fa and components of frequencies that are odd multiples of the frequency fa (3fa, 5fa, etc.). Furthermore, the Fourier converter 31 obtains information Vα(t) related to the temporal change of the output voltage from the communication circuit 30 of the charging device 3 . In a certain example, the information Vα(t) is measurement data of a temporal change in the output voltage measured by the voltage monitoring unit 28 . Also, in another example, the measurement data of the output current is corrected to the information Iα(t) as described above, and the above measurement data of the output voltage is corrected correspondingly to the correction of the information Iα(t). . Next, data on which the above-mentioned correction has been performed from the measurement data is obtained as information Vα(t) in the Fourier transformer 31 . Next, the Fourier transform 31 performs Fourier transform on the information Vα(t) (S122). By doing so, a frequency spectrum Vβ(f) for the output voltage is generated, and the frequency characteristic of the output voltage is calculated. Spectrum Vβ(f) includes components of frequency (specific frequency) fa and components of one or more frequencies that are integer multiples of frequency fa. In a certain example, the frequency spectrum Vβ(f) of the output voltage includes a component of the frequency fa and a component of an odd multiple of the frequency fa (3fa, 5fa, etc.). Next, the calculator 32 acquires the spectrum Iβ(f) of the output current and the spectrum Vβ(f) of the output voltage, and performs calculations using the spectrum Iβ(f) and Vβ(f) (S123). In the calculation in S123, the autocorrelation function Corr(I, I) of the information Iα(t) related to the temporal change of the output current is calculated from the frequency spectrum Iβ(f). Next, from the spectrum Iβ(f) and Vβ(f), the relationship between the information Iα(t) related to the temporal change of the output current and the information Vα(t) related to the temporal change of the output voltage is calculated. The cross-correlation function Corr(I, V). Next, the calculator 32 performs calculations using the calculated autocorrelation function Corr(I, I) and cross-correlation function Corr(I, V) (S124). By the calculation of S124, the impedance characteristic of the battery pack 6 (one or more batteries 7) is calculated. In a certain example, by dividing the cross-correlation function Corr(I, V) by the auto-correlation function Corr(I, I), the components contained in the spectrum Iβ(f), Vβ(f) (spectral component ) to calculate the impedance for each of the frequencies. The diagnosis server 5 diagnoses the state (deterioration state) of the battery pack 6 based on the calculated impedance characteristics. In addition, when the measured data of the output current is used as information Iα(t), the information Iα(t) that deviates from the current waveform centered on zero, such as the portion of the current waveform at frequency fa, is is Fourier transformed. In this case, the data of the frequency spectrum Iβ(f) obtained by Fourier transform is corrected corresponding to the aforementioned deviation of the portion of the current waveform at the frequency fa. Next, the impedance characteristic is calculated using the data obtained by performing the above-mentioned correction from the data of the spectrum Iβ(f). Also, when using the measurement data of the output voltage as information Vα(t) and obtaining the frequency spectrum Vβ(f) by Fourier transform, it is the same as using the measurement data of the output current as information Iα(t). In the same way, appropriate corrections are made to the data of the spectrum Vβ(f). Next, the impedance characteristic is calculated using the above-mentioned corrected data from the data of the frequency spectrum Vβ(f). As described above, in this embodiment, the impedance characteristics of the battery pack 6 are calculated from the information Iα(t) and Vα(t) in the same way as the so-called rectangular wave impedance method. Here, the diagnosis of the state of the battery (battery pack) based on the rectangular wave impedance method and impedance characteristics is disclosed in Reference 1 (Japanese Patent Laid-Open No. 2014-126532) and Reference 2 (Electrochimica Acta vol .246 (2017) p.800‐p.811). In this embodiment, the output current to the battery pack 6 is controlled. Therefore, in the calculation of the impedance characteristic, the autocorrelation function Corr(I, I) of the information Iα(t) related to the temporal change of the output current is used. As described above, in the present embodiment, the superimposed current obtained by superimposing the current waveform (rectangular wave current) of the frequency fa on the reference current which is direct current is set by the current waveform superimposing unit 23 . Next, the output current setting unit 25 controls the output current to the battery pack 6 in a state where the set superimposed current is output, and charges the battery pack 6 by the output current. By controlling the output current as described above, the measurement data of the temporal change of the output current and the measurement data of the temporal change of the output voltage synchronized with the output current can be used in the battery pack 6 In the diagnosis of the state of the battery pack 6 such as the calculation of the impedance characteristic. Therefore, the information used for diagnosing the state of the battery pack 6 can be easily obtained when the battery pack 6 is being charged. In addition, in the present embodiment, the current waveform superimposing unit 23 sets the superimposed current in a state where the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. Therefore, even when the output current is controlled in a state where the overlapping current is output, the output current can be continuously supplied to the battery pack 6 over time, and the battery pack 6 can be continuously charged over time. As a result, the battery pack 6 is properly charged. Also, in the present embodiment, the current waveform setting unit 22 sets the amplitude of the current waveform to be 5% or less with respect to the current value of the reference current. Therefore, by controlling the output current in a state where the overlapping current is output, the deviation between the current value of the output current and the current value of the reference current (command current value during charging) is reduced. Thus, the battery pack 6 is caused to be more properly charged. In addition, in the present embodiment, the output current setting unit 25 performs feedback control on the output current in a state where the deviation between the target current value and the detected current value is close to zero. For example, when an overlapping current is set such that the amplitude of the current waveform becomes 5% or less with respect to the current value of the reference current, the output current setting unit 25 sets the current value of the output current (detection current value) to the reference current. Feedback control is performed when the difference between current values (command current values during charging) falls below 5%. As a result, the deviation between the current value of the output current and the current value of the reference current (command current value during charging) is further reduced, enabling the battery pack 6 to be charged more appropriately. Also, in the present embodiment, when the waveform setting command is not generated, etc., the current waveform is not set, and the output current setting part 25 controls the output current to the battery pack 6 in a state where the set reference current is output. the output current. Therefore, the control model related to the output current to the battery pack 6 can be selected according to the situation such as whether or not it is necessary to obtain information used for diagnosis of the battery pack 6 . In addition, in this embodiment, the diagnosis server 5 calculates the impedance characteristic of the battery pack 6 as described above based on the measurement data of the temporal change of the output current and the measurement data of the temporal change of the output voltage. . Therefore, the impedance characteristics are appropriately calculated using the measurement data, and the state of the battery pack 6 is appropriately diagnosed. (Modification) In a modification, the current waveform setting unit 22 further sets current waveforms at frequencies that are one or more integral multiples of the frequency fa in addition to the current waveform at the frequency (specific frequency) fa. Next, the current waveform superimposing unit 23 superimposes the current waveform of one or more frequencies that are an integral multiple of the frequency fa on the reference current in addition to the current waveform of the frequency fa to set the superimposed current. In this modified example as well, the output current setting unit 25 controls the output current to the battery pack 6 in a state where the set superimposed current is output. In this modified example, superimposed current output control is performed to superimpose current waveforms of one or more frequencies that are an integral multiple of the frequency fa in addition to the current waveform of the frequency fa. Therefore, by calculating the spectrum Iβ(f) of the output current and the spectrum Vβ(f) of the output voltage as in the aforementioned embodiment, it becomes possible to obtain Components (spectral components) are acquired at more frequencies among frequencies that are integer multiples of the frequency fa. Thereby, the impedance is calculated at more frequencies among the frequencies that are integer multiples of the frequency fa, and the state (deteriorated state) of the battery pack 6 can be diagnosed more appropriately. In a certain example, in addition to the current waveform of frequency (first frequency) fa, the current waveforms of frequencies fb and fc (fc>fb) which are two integral multiples of frequency fa are set to overlap the reference current the overlapping current. Next, the output current to the battery pack 6 is controlled in a state where the set overlapping current is output. In this case, frequency (second frequency) fb is preferably an even multiple of frequency fa, for example, frequency 2fa. Next, the frequency (third frequency) fc is preferably an even-number multiple of the frequency fa and an even-number multiple of the frequency fb, for example, frequency 4fa (=2fb). By setting the frequencies fa to fc as described above, each of frequencies that are odd multiples of frequency fa is related to frequency fb, frequencies that are odd multiples of frequency fb, frequency fc, and frequencies that are odd multiples of frequency fc Any frequency of is different. Thereby, in each of the frequency spectra Iβ(f) and Vβ(f) calculated as in the above-mentioned embodiment, more frequencies can be obtained at frequencies that are integer multiples of the frequency fa Element. Thereby, the impedance is calculated at more frequencies among the frequencies that are integer multiples of the frequency fa, and the state (deteriorated state) of the battery pack 6 can be diagnosed more appropriately. In addition, in a certain modified example, the Fourier converter 31 and the calculator 32 may be mounted on the charging device 3 . In this modified example, the frequency characteristics of the output current and the frequency characteristics of the output voltage are calculated by the charging device 3, and the impedance characteristics of the battery pack 6 are calculated. Also, in another modified example, one of the Fourier converter 31 and the calculator 32 may be mounted on the charging device 3 . Moreover, the aforementioned control of the output current (charging current) of the charging pack 6 is applicable not only to charging the battery pack 6 of the vehicle 2 but also to charging the battery packs of devices other than the vehicle 2 . According to at least one of these embodiments or examples, the charging device and the charging method superimpose a current waveform of a specific frequency on a reference current that is a direct current, and the superimposed superimposed current is set. A state in which the direction in which the superimposed current flows is continuously consistent with the direction in which the reference current flows is maintained over time. Then, in the state where the set overlapping current is output, the output current to the battery pack is controlled, and the battery pack is charged by the output current. Thereby, it is possible to provide a charging device and a charging method in which information used for diagnosing the state of the battery pack can be easily obtained when charging the battery pack. Although several embodiments of the present invention have been described, these embodiments are disclosed as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments or modifications thereof are included in the scope or gist of the invention, and are also included in the invention described in the claims and its equivalent scope.
